Adjusting device for chairs

ABSTRACT

An adjustable chair that includes a frame supporting a seat portion. The frame also supports a member on which a back portion is mounted. The seat portion is synchronously moveable with the back portion such that as the seat portion moves forwardly the back portion moves upwardly and as the seat portion moves rearwardly the back portion moves downwardly. The mechanism effecting this movement includes a feature allowing the independent movement of the back portion or the seat portion.

The invention concerns an adjusting device for chairs, wherein the seatportion and back portion in their approximately horizontal and verticaldirection respectively are movable by means of adjusting mechanisms forsynchronous movement by means of a common operating body.

A device of this type is known from EP-A-0539733. The chair described inthis publication has a moveable seat portion which when depressed ismoved downwardly and forwardly and thereby causes a lowering of the backportion of the chair in order to provide a more convenient sittingposition.

The requirements for the design of chairs, and especially work andoffice chairs, are becoming increasingly stringent with regard to thecorrect adjustment of the chair, i.e. the individual adaptation to theuser in order to achieve a correct and comfortable sitting position.This requirement is important since such chairs are used over a longperiod of time, with the result that an incorrect adjustment feelsuncomfortable and leads to harmful sitting positions.

An increasing number of adjusting mechanisms for chairs have thereforebeen developed, which permit adjustment both of the back in the heightdirection and the seat portion forwards and backwards, thus enabling thechair to be adapted to the person's individual body size. Tilting chairsrequire adjustment of the spring resistance both for backward tilt andforward tilt. In addition further adjustments can be made both ofsitting angles, seat heights, armrest heights, width between armrests,etc., with the result that it can often be a problem for the user tounderstand and operate the correct levers in order to obtain therequired position. The result of this is that, after originally havingfound an approximately suitable position, the user often does notperform the further adjustments. With so many adjustment levers andwheels (one chair advertises over 20), the task of adjusting the chaircan appear so complicated that the user does not even attempt to adjustit to his requirements, and to his size and weight.

There is therefore a requirement to simplify the adjustment, while stillachieving the best possible functionality and preferably also means forresisting tilting.

The object of the present invention is to provide an adjusting devicewhich permits such a simple adjustment. Thereby the size of thechairbody shall be adjusted to a depth to the size of the user.

This is achieved with an adjusting device of the type mentioned in theintroduction, which is characterized by the features which are indicatedin the patent claims.

In the invention the size of the chair body is adjusted to adapt to thesize of the user. The basis for the invention is that most adjustmentspreferably should be capable of implementation with a simple adjustingmechanism, preferably a lever or a wheel. By turning such a wheel ormoving such a lever it should therefore be possible to perform basicadjustments which will provide satisfactory functionality for mostpeople. The parts move simultaneously in relation to one another in a"normal relationship". This adjustment, which automatically andsimultaneously will adjust both the seat portion and the back portion,is based on the fact that large people require a large chair body, whilea correspondingly smaller chair body is best for smaller people. Theadjustment possibilities for the backrest and the seat portion havetherefore been linked, these two main components of the chair eitherbeing pushed from each other or drawn towards each either by a simplerotating movement of the adjusting wheel or lever. Thus, by means of asimple hand maneuver, the user will be able to perform a principaladjustment of the chair (both of seat depth and backrest height). It isessential that both parts of the chair should move and not only thebackrest, since the chair body's tilting point should be locateddirectly below the body weight whether the user is small or large. Itwill be possible to achieve the same "normal relationship" displacementbetween these parts by locking the seat and pushing the backrestobliquely backwards and upwards, but in this case the body weight inrelation to the chair body's tilting point will be wrong for one half ofthe body size. The term "normal relationship" should be understood tomean that the chair's functions are arranged so as to movesimultaneously in a certain relationship to one another, thus providingsatisfactory conditions for different body sizes.

Even though this kind of automatic adjustment where the back portion andthe seat portion are pushed synchronously from each other, or drawntowards each other will be adequate for most people, nevertheless it isdesirable to also be able to adapt the chair to, e.g., people with veryshort legs and a very long upper body, i.e. people who perhaps thusrequire a short seat surface and a high back.

Thus it is a further object of the invention to provide, in addition tothe principal adjustment, the possibility of also being able to performan individual adjustment of the seat and the back portion respectively.This object is also achieved by features which are indicated in thepatent claims.

The individual adjustment is performed in the invention preferably inconnection with the back portion and performed manually by means of alever which influences an engagement mechanism, thereby permitting afree movement of the back portion. A "specially adjusted" chair of thiskind in which there is a deviation from the normal relationship betweenseat depth and back height could be difficult to have normalized for anew user. In order to be able to bring the chair back to a normalrelationship, for this purpose there is provided a release device whichcomes into force during continued operation of the principal adjustingmechanism for the seat portion/back portion and which causes the backportion to be automatically moved back from its special position to thenormal position in relation to the seat portion, with the result thatthe continued operation will take place synchronously between these twoparts until someone again employs the release device.

Just as there is a requirement to adjust the chair body's "size" toconform with the user's size, there will also be a requirement for acorresponding adjustment of the seat portion's suspension and theseat/chair body's tilting resistance respectively. For this purpose theinvention can be combined with the device which is described in thesimultaneous Norwegian patent application no. 955140 according to whichseat/back portion's tilting resistance means are adjusted in step withthe general adjustment of the chair, with the result that when the seatsurface is extended (and the backrest raised) the tilting resistance isincreased, and will decrease when the seat surface is shortened (and thebackrest lowered). This adjustment can also be adapted individually in aspecial embodiment and is returned to the normal relationship when theprincipal operating body is employed.

The different adjusting mechanisms are preferably designed as mechanicaldevices, but they can also be designed to act via hydraulic or pneumaticcylinders. In special embodiments the adjusting mechanisms can also beelectrically operated. The essential feature of the invention consistsin the actual adjustment facility, where several functions alter in amutually determined relationship--"the normal relationship"--by means ofan operating movement. Next, that this mutual relationship can bedeviated from in order to satisfy special requirements, but that as soonas the principal operating body is employed the "normal relationship"will be restored.

The invention will now be illustrated in more detail by means of anembodiment which is illustrated in the drawing, which shows in a purelyschematic form:

FIG. 1 a side view which illustrates the possibilities for movementwhich are obtained by means of the invention,

FIG. 2 a schematic principle drawing for a version where a toothed rackis employed,

FIG. 3 a schematic view corresponding to FIG. 2 which illustrates aversion with belts,

FIG. 4 a partial view in perspective which illustrates the extraadjustment possibility with release device for the chair's back portion,and

FIG. 5 a sectional view for more detailed illustration of the version inFIG. 4,

FIG. 6 is a schematic view showing the hydraulic or pneumatic connectedpressure cylinders of claim 9,

FIG. 7 a schematic view showing the electrical mechanism of claim 14.

FIGS. 1 and 2 illustrate a first embodiment of an adjusting device wherea chair's seat and back portions are movable in their longitudinaldirection and height direction respectively by means of a commonadjusting mechanism (operating body).

In FIG. 1 a chair 1 is illustrated which comprises in the known manner abasic frame with a column on which there are mounted a seat portion 2and a back portion 3 which are illustrated in a position with extendedlines and with dotted lines in an alternative second extreme position onthese two parts. In the first position the seat portion 2 is pushed asfar forward as possible, while the back portion 3 is pushed into itsuppermost position. This is achieved by turning the wheel 4 in thedirection of the arrow A, thus causing the seat portion 2 to be moved inthe direction of the arrow A1, while the back 3 is moved in thedirection of the arrow A2. By turning the wheel 4 in the oppositedirection, i.e. anticlockwise, as shown by the arrow B, the chair seat 2will move backwards in the direction of the arrow B1 to an innermostposition which is illustrated by dotted lines 2', while at the same timeas the wheel is turned in the direction of the arrow B the back portion3 will be moved downwards in the direction of the arrow B2 to theposition 3'.

In FIG. 2 there is a purely schematic illustration of how this movementof the seat portion and the back portion in relation to the chair'sframe 5 can be achieved. On the underside of the chair seat 2 there areprovided one or more toothed tracks 6 which are engaged with one or moretoothed wheels 7 which can be rotated by means of the wheel 4. Thetoothed wheel 7 is also engaged with an adjusting wire or a steel band 8provided with holes or teeth, which extends from the area at the frame 5through a supporting tube 9 for the back 3 to be attached to the saidback at its upper section 8A.

By turning the wheel 4, i.e. turning the toothed wheel 7, the chairportion will move, e.g., in the direction which is illustrated by thearrow A1 and the back 3 will move in the upward direction as indicatedby the arrow A2. The back 3 is moved upwards by means of the flexiblewire or the band 8 which is pushed in the tube 9, thereby raising theback, which is also equipped with, e.g., a telescopic part 10 which canbe moved in the upper section 9A of the tube 9.

This design can be varied within wide limits, with other mechanicalsolutions also being envisaged as well as hydraulic, gas-operated orelectrical systems for synchronous movement of the seat portion 2 andthe back portion 3. An example of a second embodiment of this kind isschematically illustrated in FIG. 3. In this embodiment too theadjustment is performed by means of a wheel 4, but in this case toothedracks and toothed wheels are replaced by an endless band or a strapwhich is passed over return rollers 22, 23, 24. The band or the strapwhich is designated 25 may be a flat steel band, but can also be ofanother material and it will also be possible to use steel wires. Thechair portion is mounted on the upper part of the horizontal part of theband by suitable attachment means 27, which are not illustrated in moredetail, while the back portion 3 is attached in a similar fashion byattachment means 26 to the rear part of the band 25. By turning thewheel 4, the same pattern of movement will be obtained as in theprevious example. It should be clear that it will also be possible toemploy hydraulic or pneumatic aids as shown in FIG. 6, at referencenumeral 30, or also electrical operation as shown on FIG. 7. atreferemce numeral 40, in order to provide a corresponding pattern ofmovement.

FIGS. 4 and 5 illustrate how an individual height adjustment or releasedevice can be undertaken for the back portion 3. In this connection itshould be pointed out that it will be possible to perform a reversal ofthe positions of the adjustment means release device without anytrouble, so that it will be possible to also employ the adjustment whichis described in the following section in connection with the backportion for the seat portion, while the back portion is designed withoutthe possibility for such an individual adjustment. In principle it willonly be necessary to have an individual adjustment either of the backportion or of the seat portion.

FIGS. 4 and 5 show a section of the support device for the back with asupport tube for the chair back 3, which in this embodiment isdesignated as sleeve 12. For the individual adjustment an operating arm11 is employed. The operating arm 11 is rotatably mounted on the sleeve12 which supports the chair back portion 3. The latter is supported bythe upper cross bracket 13. The sleeve 12 is slidably provided on a tube14 which extends vertically up from the chair frame. This tube 14 issplit in the longitudinal direction. On each side of the split 15 a hole16 is provided in the edges of the tube at regular intervals, hole 16 ofone tube edge being located horizontally above hole 16 of the other tubeedge, thus creating a vertical row of hole pairs.

In the tube there is provided a band (rod) 8 which supports a singleprojecton 17 (in the figure the operating arm rests on this projectionand it is apparent that the notch or indentation 20 has a shorter depththan the height of the projection). Furthermore, the operating arm 11 isspring loaded in a counterclockwise direction by means of a coil spring18 one end of which rests on the bracket 19 which supports the arm 11.

When the backrest is to be released from the band 8, the lower end ofthe arm is pressed in, thus causing the arm to be rotated clockwise. Anindentation or notch 20 of the arm is thereby brought out of engagementwith the projection 17. The seat back is then moved up or down,whereupon the arm is released. Two hooks 21 at the upper section of thearm can thereby each slip into its hole 16 at the tube edges.

The arm is designed with an inclined plane on either side of the notchin the extension, or region, adjacent the notch. When the seat back isto be returned to normal, the wheel is operated which causes the bandand the seat to move. When the projection 17 comes into contact with oneof the inclined planes or tilted sections of the arm on one side or theother of the above-mentioned indentation of the arm, the arm is rotatedby the projection in the clockwise direction, thus bringing the hooksout of the holes and the projection is inserted into the indentation.When the height of the projection is so great that the hooks therebycannot touch the band, the seat back is moved up and down while at thesame time the seat is moved forwards and backwards, the normal settingfor these components having once more been attained.

By means of this mechanism the following advantages are obtained:

a) the chair is easily operated by means of a one-grip handle (manyfunctional objects and tilt resistance means are adjusted simultaneouslyin a mutually determined "normal relationship",

b) many adjustment possibilities for the person who wishes an even moreindividual adaptation (the normal relationship is interrupted),

c) the chair will always return to the normal relationship (between thedifferent functions) when a new user operates the principal operatingbody.

Many modifications will be possible within the scope of the invention.As mentioned, the mechanisms for seat portion and back portion can beexchanged, the design of the movement mechanisms can be varied and itwill be possible for a person skilled in the art to also provide thesame pattern of movement by other means than mechanical media, e.g.hydraulic, pneumatic or electrical means. A link arm mechanism can alsobe employed in which the arms can be retracted/unfolded and where duringsuch manipulation the mechanism is controlled in such a manner that theposition of the seat and/or the armrest is adjusted as required. Allsuch embodiments are intended to fall within the scope of the invention.It is also stated above that the device according to the invention canalso be combined with an adjusting device for the chair seat's tiltingresistance, e.g. of the type which is described in the applicant's NOapplication 955140. The seat movement which governs the tiltingresistance can simultaneously control the position of the back portion.Similarly, an adjustment of the armrests can also be incorporated, withthese being adjusted to different heights in relation to the user. Anadjusting mechanism of this kind can be designed in a similar manner tothe device according to the invention, either as a separate device orcombined with the device according to the invention.

What is claimed is:
 1. A chair having a front portion and a rearportion, said chair including a seat portion, a back portion, and anadjusting mechanism for adjusting the position of said seat portion andsaid back portion, said seat portion being supported for movementforwardly and rearwardly of the chair, said back portion being supportedfor movement upwardly and downwardly relative to the chair, saidadjusting mechanism permitting synchronous movement of said seat portionforwardly and said back portion upwardly and also permitting synchronousmovement of said seat portion rearwardly and said back portiondownwardly, characterized in that for individual adjustment the backportion or the seat portion can be released from the adjustingmechanism.
 2. A device according to claim 1, characterized in that theback portion and the seat portion can be released by means of a releasedevice having releasable locking means for connection to the adjustingmechanism.
 3. A device according to claim 2, characterized in that thelocking means comprise a spring-loaded locking arm with a notch havingthe same shape as a projection on the mechanism, and that the springforce is directed towards the mechanism to secure the projection in thenotch.
 4. A device according to claim 3, characterized in that the notchhas a shorter depth than the height of the projection, that the end ofthe arm facing the mechanism has at least one hook or a pair of hooks,and further including in the chair's supporting body a row of holeswhich is adapted to work together with the pair of hooks.
 5. A deviceaccording to claim 4, characterized in that the arm adjacent the notchis constructed with an inclined plane on each side of the notch.
 6. Achair having a front portion and a rear portion, said chair including aframe, a seat portion supported for linear movement relative to saidframe forwardly and rearwardly of the chair, support means carried bysaid frame, a back portion supported for linear movement relative tosaid support means upwardly and downwardly of the chair, and anadjusting mechanism for adjusting the position of said seat portion andsaid back portion, so that when said seat portion moves forwardly of thechair said back portion simultaneously moves upwardly of the chair, andfurther so that when said seat portion moves rearwardly of the chairsaid back portion moves downwardly of the chair.
 7. A device accordingto claim 6, characterized in that the adjusting mechanism comprises atoothed rack and band connected by a joint toothed wheel.
 8. A deviceaccording to claim 6, characterized in that the adjusting mechanismincludes hydraulic or pneumatic connected pressure cylinders forpermitting synchronous operation of said seat portion and said backportion.
 9. A device according to claim 6, characterized in that theadjusting mechanism includes an endless belt, where the seat portion andthe back portion are attached to an upper track and a rear track of thebelt respectively.
 10. A device according to claim 6, characterized inthat the adjusting mechanism includes an electrical mechanism forpermitting synchronous operation of said seat portion and said backportion.